This application is related to and claims priority from Japanese Patent Applications No. 2001-27441 filed on Feb. 2, 2001, No. 2001-103546 filed on Apr. 2, 2001, and No. 2002-17297 filed on Jan. 25, 2002, the contents of which are hereby incorporated by reference.
The present invention relates to a solar radiation detection unit for a vehicle for detecting intensity of solar radiation which enters a vehicle compartment and a direction of entry thereof, and a vehicle air conditioner using the same. More particularly, the present invention relates to improvement in precision of a detected value for an amount of solar radiation in the vehicle solar radiation detection unit.
Conventionally, a solar radiation detection unit for a vehicle and a vehicle air conditioner using the same have been disclosed in, for example, JP-A-2000-62433. In this official gazette, on the basis of an amount of solar radiation detected by a solar radiation sensor located on an instrument panel, through the use of a position of the vehicle, the solar position, obstacles, meteorological information, and the like that have been obtained by a navigation system, presence or absence and direction of entry of solar radiation entering the vehicle are computed to correct the solar radiation amount detected by the solar radiation sensor, thereby an amount of solar radiation to each seat area within the vehicle compartment is detected.
The solar radiation detection unit, however, is remained at correction of the solar radiation amount based on presence or absence and direction of entry of solar radiation entering the vehicle, and any influence on the solar radiation amount to which the vehicle is actually received is not been sufficiently studied by taking into consideration the vehicle-side condition, inclination state of the road, and the like. Accordingly, the solar radiation amount cannot be detected with high accuracy.
In view of the above-described points, it is one object of the present invention to provide a solar radiation detection unit for a vehicle capable of detecting an amount of solar radiation more precisely.
It is another object of the present invention to provide a vehicle air conditioner using a solar radiation detection unit, capable of performing more comfortable air-conditioning operation for passengers of the vehicle.
A solar radiation detection unit for detecting intensity of the solar radiation entering a vehicle compartment according to the present invention is provided in a vehicle equipped with a navigation system which detects the present position and a travel direction of the vehicle, and guides the travelling of the vehicle based on the detected present position and the detected the travel direction of the vehicle, and road information including at least information concerning structures around the road previously stored. According to the inventor""s study, in the solar radiation amount entering the vehicle, by calculating a direction of entry of solar radiation entering the vehicle relative to the solar position and the travel direction of the vehicle, heat-receiving amount entering into the vehicle is determined. This entering direction of the solar radiation has a solar radiation attack angle (xcex8) and a solar radiation lateral angle (xcfx86) with respect to the solar position and the travel direction of the vehicle. A quantity of heat received by the passenger by solar radiation and a quantity of heat received by the interior of the vehicle compartment by solar radiation are different based on the solar radiation attack angle (xcex8). Incidentally, the quantity of heat received by the passenger seated on the seat becomes maximum when the solar radiation tack angle (xcex8) is close to about 30xc2x0 C., and the quantity of heat received by the interior of the vehicle compartment becomes maximum when the solar radiation attack angle (xcex8) is close to about 60xc2x0 C. Accordingly, by accurately detecting the solar radiation attack angle (xcex8) entering the vehicle, the solar radiation amount entering the vehicle can be detected more accurately.
According to the present invention, the solar radiation detection unit has solar-radiation direction calculating means for calculating the direction of entry of solar radiation and solar-radiation amount calculating means for determining the solar radiation amount entering the vehicle. The solar-radiation amount calculating means corrects the solar radiation amount on the basis of the information unique to the vehicle, so that the solar radiation direction entering into the vehicle is determined on the basis of the solar position information and the road information. The solar-radiation amount calculating means is capable of detecting a more accurate amount of solar radiation by correcting the solar radiation amount entering the vehicle specifically on the basis of, as the information unique to the vehicle, the vehicle height, color of the vehicle body, position of the seat of the vehicle, positional relationship between the seat and position, size, angle and permeability characteristic of the widow glass in the vehicle.
In a vehicle traveling on a road, the vehicle horizontal direction varies depending upon the angle of inclination of the road. According to the present invention, solar-radiation direction calculating means for calculating the solar radiation direction entering the vehicle reads solar position information and road information concerning the vicinity of the vehicle position including at least information on the angle of inclination of the road to determine the solar radiation amount on the basis of the solar position information and the road information, whereby the solar radiation attack angle (xcex8) is determined accurately, and a more accurate amount of solar radiation is detected. In the present invention, when it is determined that the solar radiation attack angle (xcex8) is within a predetermined range, correction is made such that the solar radiation amount is made larger, whereby the quantity of heat received by the passenger by solar radiation is corrected to thereby enable comfortable air conditioning operation.
The solar radiation sensor for outputting a detection signal responsive to intensity of solar radiation is constructed of, for example, a well-known photodiode. Since the photodiode has generally low sensitivity characteristic within a visible light area (from 400 nm to about 800 nm) of wave length of sunlight, generally the output characteristic becomes maximum when the solar radiation attack angle (xcex8) entering the vehicle is close to 90xc2x0, and as the solar radiation attack angle (xcex8) becomes smaller than 90xc2x0. Further, the output characteristic is more decreased.
According to the present invention, on the basis of the calculation result of the solar-radiation direction calculating means, the solar radiation amount is determined by correcting a detected value from the solar radiation sensor. Accordingly, the solar-radiation amount calculating means is capable of determining an amount of solar radiation consistent with the quantity of heat received by the passenger and the vehicle. Thus, a more accurate amount of solar radiation is detected. As regards a corrected value corresponding to the quantity of heat received by solar radiation, specifically, the correction is made such that it becomes maximum in a range of 0xc2x0 and 75xc2x0 in which the output characteristic of the solar radiation sensor is decreased. Therefore, it becomes possible to detect a high precision amount of solar radiation corresponding to the heat-receiving amount received by the passenger and the vehicle.
Since the heat-receiving amount of the vehicle is affected by the characteristic of the window glass, the corrected value is further corrected in accordance with, for example, type of the window glass of the vehicle, so that the solar radiation entering the vehicle is detected with higher precision.
In order to determine the solar radiation direction (xcex8, xcfx86), information unique to the vehicle including at least the shape of the vehicle in addition to the angle of inclination of the road is inputted into the navigation system in advance, the solar radiation direction (xcex8, xcfx86) entering the vehicle is accurately determined in accordance with the information unique to the vehicle, and an increment of the quantity of received heat entering the vehicle is obtained accurately and the detection precision is further improved.
In addition to the present position and the travel direction of the vehicle, meteorological information means corresponding to the area is inputted into the navigation system, so that weather information such as, for example, intensity of solar radiation, an amount of clouds, and rainy weather is used among the meteorological information for further improving the detection precision of solar radiation.
In the present invention, there is provided solar-radiation amount correction and storage means which stores a correction coefficient corresponding to the solar radiation direction (xcex8, xcfx86) in order to determine the solar radiation amount entering the vehicle correspondingly to a direct-reaching amount of solar radiation for reaching the earth""s surface that has been determined from the solar position, and the correction coefficient is determined from the solar-radiation amount correction and storage means on the basis of the solar radiation direction (xcex8, xcfx86) determined by the solar-radiation direction calculating means. Solar-radiation amount calculating means is provided for determining the solar radiation amount entering the vehicle through the use of the correction coefficient and the direct-reaching amount of solar radiation, so that the solar radiation amount corresponding to the solar radiation direction (xcex8, xcfx86) entering the vehicle is detected. Accordingly, a high precision amount of solar radiation corresponding to the quantity of heat received by the passenger and the vehicle is detected. The solar position determined by solar position retrieval means, road information including positions and height information of roads around the vehicle and structures around the roads which have been detected by the navigation system, and information unique to the vehicle by vehicle information input means having information unique to the vehicle including at least the shape of the vehicle are read. Further, the solar-radiation direction calculating means which determines the solar radiation direction (xcex8, xcfx86) entering the vehicle on the basis of the solar position, road information and information unique to the vehicle is provided. Since the solar radiation attack angle (xcex8) entering the vehicle differs with, for example, the shape of the vehicle, the angle of inclination of the road and the like, the solar radiation attack angle (xcex8) is determined accurately by inputting these information. Thus, a higher precision amount of solar radiation is detected as compared with the solar radiation amount detected only by the solar radiation sensor.
In an air conditioner for a vehicle using this solar radiation detection unit, control means is provided. When solar radiation from the solar position enters the vehicle, the control means performs a flow amount control of conditioned air to be blown into respective air outlet for plural areas within the vehicle compartment, on the basis of the solar radiation amount determined by the solar-radiation amount calculating means. Accordingly, it is possible to perform blowing control of the conditioned air in accordance with the solar radiation amount entering the vehicle to thereby improve the comfort of the passengers within the vehicle compartment.